Example of “Continuous Box Type Temporary Levee” that ensures effective flood control

Levees along rivers and coastal areas play an extremely important role in Japan, where typhoons visit every year. However, due to various reasons, there are approximately 1,500 km of uncompleted levees that are insufficient in height and width. The risk of flood damage due to overflows from rivers and levees has increased due to the recent frequent abnormal rainfall, but full-scale levee raising requires time to secure new land and complete the raising. Therefore, emergency measures are being taken by “temporarily raising the levees” until the main levees are completed. In order to raise the levees (secure the height), it is necessary to secure the necessary width (land for levee construction). However, it is not always easy to secure land for this purpose in some areas. Large sandbags, which are often used for “temporary embankment raising” due to their low cost, have weaknesses such as low water sealing performance, risk of tipping over or being washed away due to lack of integrity, and short service life. Large sandbags used for temporary raising have the risk of leaking water through the gaps and eroding the backwall (demonstration test). The “Continuous Box Type Temporary Embankment” achieves high water sealing performance, stability due to its excellent integrity, short construction period, and long service life at the same time. This method, which can add high flood control effect to incomplete levees with insufficient height from tomorrow, will be introduced in detail with specific examples with pictures. Please take a look at this method, which can be applied to small-scale restoration work and boasts a wealth of experience in its adoption by municipalities such as cities, wards, towns, and villages.

What is Continuous Box Type Steel Frame?

ここで紹介する事例では、すべて連続箱型鋼製枠を採用しています。

連続箱型鋼製枠は、亜鉛メッキ鉄線製の格子状のパネルをコイル連結したカゴ（鋼製枠）を複数接続した構造で、分割・延長・屈曲させて設置できます。鋼製枠の内側に不織布を張り、現地発生土や砕石、栗石等を中詰めすることで、連続した土堤を簡単・迅速に構築でき、土留め、堤防嵩上げ工、仮締切工等に使用できます。

Outline and Features of Continuous Box Type Steel Frame "MAXWALL

Maxwall uses lattice-like panels made of galvanized iron wire, which are durable enough to withstand use for about 10 years, making it suitable for temporary construction over a long period of time. Because of its high durability and the fact that it does not require any filling material, Maxwall was introduced in the areas affected by the Great East Japan Earthquake as a temporary earth embankment and earth retaining system for raising embankments and embankments, and has been installed in coastal areas using locally generated soil and concrete rubble recycled from rubble due to the shortage of materials such as crushed stone. The following is a brief introduction of its outstanding features.

Feature 1: High stability

Large sandbags often used for temporary construction are not connected and not integrated, making them vulnerable to external forces and unstable, such as collapsing if the load is concentrated in one place. Maxwall, with its continuous steel frame, can withstand more than four times the external force (approximately 16 kN) of large sandbags, demonstrating its high stability.

Feature 2: Watertightness due to soil continuity

The inner frame (the red frame in the figure below) is not covered with non-woven fabric, and the continuous filling material such as sand and soil ensures high water sealing performance that cannot be achieved with large sandbags.

Feature 3: High durability and can be used as a long-term temporary installation

While large sandbags can be used for only about 6 months to 3 years, Maxwall has a durability of more than 10 years on land and in the soil, and about 5 years in areas where seawater splashes. In the Great East Japan Earthquake, Maxwall was used for a long period of time in coastal areas as a temporary construction material for revetments and earth retaining works.

 

Feature 4: Any filling material can be used, including earth, sand, crushed stone, and locally generated soil.

It can be used not only for earth and sand, but also for crushed stone and chestnut stone, and can also be used as a residual concrete formwork.

 

Feature 5: Can be stacked, split, extended, and bent

The standard size (one unit) consists of a series of ten 1-meter cubic steel frames (cells), which can be freely divided, extended, and bent to suit the scale of construction and site conditions. It can also be stacked in tiers, allowing it to flexibly adapt to the shape of the site.

 

Feature 6: 25% shorter construction period than conventional large sandbags

It does not require skilled labor and can be installed by five people for approximately 40 meters per day. This is an approximate 25% reduction in construction time compared to large sandbags.

Examples in embankment raising and temporary embankments

The following is an example of how the continuous box-type steel frame “Maxwall” was actually used to build a temporary embankment.

First-class river Nakanokuchi River embankment raising in Matsuhashi, Niigata Prefecture

In this case, the levee height was insufficient for a section of approximately 460 m, so it was necessary to raise the levee. The conventional method of raising the embankment with large sandbags did not have sufficient water sealing performance, and it was difficult to ensure durability for continuous use over a long period of eight years. As a solution, Maxwall was adopted, which boasts a service life of about 10 years on land, high water sealing performance due to its continuous embankment structure, and high stability due to its integrated nature.

At this construction site, the top edge was compacted with plates and other materials, and embankment materials were used for filling to improve water sealing performance.

 

Saitama Prefecture Buro River Emergency Flood Control Measures Construction

 

Omori River and other river maintenance work, Miyagi Prefecture

 

Aomori Mabuchi River Outer River Maintenance Work

 

First-class river Nakanokuchi river embankment raising construction

Inquiry about Continuous Box Type Steel Frame

We introduced the “Continuous Box Type Temporary Embankment” solution using Maxwall, a continuous box type steel frame, as a new option to solve conventional problems in embankment raising projects such as temporary embankments.

Maxwall is a temporary material that can withstand long-term use and shorten the construction period. In addition, it is an excellent construction method that reduces overall costs because it does not require special skilled workers or skilled labor.

It has been widely adopted by local governments, especially as a solution for sites where land is limited or a high service life is required. To learn more about Maxwall or to contact a representative, please visit the following link

> Taiyo Kogyo Corporation, “Maxwall” continuous box-type steel frames